LV8731V
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18
Current Control Operation Specification
• Sine Wave Increasing Direction
Figure 15. Sine Wave Increasing Direction
STEP
Coil Current
fchop
Current mode
CHARGE SLOW FAST CHARGE SLOW FAST
Set Current
Set Current
Forced
CHARGE
section
• Sine Wave Decreasing Direction
Figure 16. Sine Wave Decreasing Direction
STEP
Coil Current
fchop
Current mode
CHARGE SLOW FAST CHARGE FAST
Set Current
Set Current
CHARGE SLOW
Forced
CHARGE
section
Forced
section
In each current mode, the operation sequence is as
described below :
• At rise of chopping frequency, the CHARGE mode
begins. (In the time defined as the “blanking time”, the
CHARGE mode is forced regardless of the magnitude
of the coil current (ICOIL) and set current (IREF))
• The coil current (ICOIL) and set current (IREF) are
compared in this blanking time.
− When (ICOIL < IREF) state exists ;
The CHARGE mode up to ICOIL ≥ IREF, then
followed by changeover to the SLOW DECAY
mode, and finally by the FAST DECAY mode for
approximately 1 μs
− When (ICOIL < IREF) state does not exist ;
The FAST DECAY mode begins. The coil current is
attenuated in the FAST DECAY mode till one cycle
of chopping is over
Above operations are repeated. Normally, the SLOW
(+FAST) DECAY mode continues in the sine wave
increasing direction, then entering the FAST DECAY mode
till the current is attenuated to the set level and followed by
the SLOW DECAY mode.
